In E.B White's masterpiece Charlotte's Web, the parents of Fern and Avery Arable watch nervously as the children charge off toward the Ferris wheel and frozen custard, the merry-go-round and wonderful music of a bustling fairground. "Well, they've got to grow up some time," Mr. Arable says to his wistful missus. "And a fair is a good place to start, I guess."

A fair is both a world apart and the world in miniature, sharply distilled (if slightly distorted), where the earnest industry of the 4-H pavilion exists alongside the low appetites of the funnel-cake stand and the thrill seeking at...